Exposure to Chlorinated Water May Heighten Risk of Cancer

A new study published in the current issue of the American Journal of Epidemiology has established a link between exposure to chlorinated water and an increased risk of bladder cancer. According to researchers, ingestion of and bathing, showering, and swimming in chlorinated water can all lead to increased incidence of cancer.

The study, led by Cristina M. Villanueva of the Municipal Institute of Medical Research in Barcelona, Spain, found that Ã¢â‚¬Å“long-term THM exposure was associated with a twofold bladder cancer riskÃ¢â‚¬Â in households with high levels (50 or more micrograms per liter) of THM. (THMs, or trihalomethanes, are chemical by-products of chlorination.) Researchers discovered that these chemicals may invade the human body not only through ingestion of water, but by inhalation and dermal absorption as well. They also believe that THM that is absorbed or inhaled into the body does not go through a detoxification process in the liver, which may make the chemical much more dangerous in those situations.

The results showed that drinking highly chlorinated water raised the cancer risk by 35 percent and that swimming in chlorinated pools raised the risk by 57 percent. Those who took longer showers and baths in THM-contaminated water saw their risk of bladder cancer increase 83 percent.